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DLottmann

...If you have three pounds of snow, and one pound of moisture from condensation, we will have an increase of the weight of the snow to four ponds. Four pounds and the methamorphosis of the light snow flake into a round shape crystal can favorise avalanches.

...

Because you laught at me, I loose my credibility and people didn't try to understand some point that could save their life, they don't understand why they could be in danger. Many people don't climb because of that. it is not fun.

First off Champ, I am not laughing at you. I like that you are so interested in the snow science. Perhaps you are losing something in the translation, but much of what you are saying is incorrect, mis-explained, or just wrong. Many of your blanket statements like "round shape crystal can favorise avalanches" are 110% wrong. Rounded grains lead to stronger layers and a more stable snowpack as the season progresses. They can also create slabs when sitting on-top of weaker layers (more sharp crystals). Neither rounds, nor facets (sharp/angular crystals) are dangerous in and of themselves, but in their relation to other layers in the snow pack they can be...

Back to your idea of condensation on the snowpack.. here you are greatly exaggerating the effect of condensation on the snow surface. What I think you might be thinking of is how "Surface Hoar", or Hoar Frost forms. It grows on the surface of the snow from humidity in the air during rapid radiative cooling (calm, clear, cold nights) and later can become dangerous when it is buried by stronger snow. The weight that surface hoar adds to the snowpack is neglible, but the effect of buried surface hoar is quite noticeable as it is often the weak layer for "persistent slabs". This mechanism is not a player in our east coast avy terrain as we very rarely get the conditions to promote it... it's more a Continental (Rocky Mountain) snow climate issue where they do get lots of cold, clear, calm nights...

I don't mean to steal your credibility, but you are describing processes incorrectly (or greatly exaggerating), and even if you did describe them correctly they are not easy to observe in the field.

We should probably stop here before we start talking about vapor pressure and temperature gradients in the snowpack... but that is where this is heading...

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DLottmann

OK, one last note since I am trying to think about how to better explain the snowpack getting "heavier" as you say...

It's a combination of settlement, compression (from gravity), which is sped up by warm temps/solar. No weight is added, but the snow feels heavier because there is less porous space in the snow, less air... as it condenses, it feels heavier... these effects are vastly more pronounced than what can be added to the snowpack from humidity in the air, which is almost non-measurable.

Since you used the mirror example... the mirror weighs 6 pounds, the condensation from the shower adds how much weight to the mirror? Same with the snow, condensation from air humidity (surface hoar), adds a very negligible weight to the snow pack, and only on the surface.

I can't decide which is my favorite season here at NEClimbs. BOLTS or AVALANCHES.

LOL... right on!

Because you laught at me, I loose my credibility and people didn't try to understand some point that could save their life, they don't understand why they could be in danger. Many people don't climb because of that. it is not fun.

Champ,

No disrespect, but I don't think your credibility problems are anyone's fault but your own. It's very difficult to distinguish whether or not it's only a language barrier problem. Sometimes I can make sense of your posts and sometimes it might as well be in french. People who've climbed with you speak highly of your ability, but I'd be hard pressed to find someone who'd speak highly of your ability to make a clear point in this forum. FWIW If you really cared about your credibility, you'd reel it in a smidge.

First off Champ, I am not laughing at you. I like that you are so interested in the snow science. Perhaps you are losing something in the translation, but much of what you are saying is incorrect, mis-explained, or just wrong. Many of your blanket statements like "round shape crystal can favorise avalanches" are 110% wrong.

Dman I have a master degre in limnology. I studied the state of water from is pure crystal shape to the transformation of nitrate to acid rain. I gave you a reference, " INTERACTION BETWEEN SNOW METAMORPHISM AND CLIMATE: PHYSICAL AND CHEMICAL ASPECT", where it is state that metamorphosis of snow by humidity is important in avalanches. Saying that is incorrect, mis-explained or just wrong...your formation is military and you state that the harder think that you did in snow storm is omega first pitch as you state before.

Do I insult you? Do I say that, in a film like good morning america, you look like the guy who think that his conception of music is the good one and there is no other possibility. You cover a market, there is some people who like very strict rules and need to follow some one else in what is a great adventure. Because climbing at any level is a great adventure. But you insult people, like the person trap in Mt Jackson because she underestimate the power of the wind in her way back and stayed a live because she had the skill and intelligence to stay in a shade area.

DWK, my english is better than before. It is hard some times to understand me, I know that. But therms like condensation and mirror don't need a lot of explanation to understand that warm and humid water condense in a mirror when some one take a shower. A text like "Yes but trad or sports avalanche ?" means and understanding of what I am saying and an intention to ridiculise an other person. I can understand that a word like body x position and going to an adventure can make a reference to some think funny. But there is no attack on my credibility in those joke... and it is that kind of discussion that we had at the bottom of the cliff in the golden age.

often experiences climber don't say a lot of think because they know never say never. In the wild, there is always a situation that can't be explain. As a climber, you look at a route and can say if it is easy or hard. But you have to try it to test your judgement. In a forum, it is the same. If you think that you are right you can test what you think in a forum. It is enought humiliating to understand that what we think is good or wrong. it is a fall and every body look at you. But who can be a good climber without falling. when some one fall, you can humiliate him, saying that you are better climber, but you can also gave him beta to find the best partner ever. Nb. one of my partner didn't have academic knowledge, he can't explain scientifiquely avalanches. Even with my knowledge, I will trust him any times because he know the answer in snowfall terms...he have a pratical knowledge and he gather informations every where like a sponge and test it in the field. Thank you Mark

DLottmann

...I gave you a reference, " INTERACTION BETWEEN SNOW METAMORPHISM AND CLIMATE: PHYSICAL AND CHEMICAL ASPECT", where it is state that metamorphosis of snow by humidity is important in avalanches...

Do I insult you?...But you insult people, like the person trap in Mt Jackson because she underestimate the power of the wind in her way back and stayed a live because she had the skill and intelligence to stay in a shade area.

I don't know why I keep trying.

WARNING: SERIOUS SNOW GEEK TALK COMING BELOW!

You are talking about TWO different processes, confusing the transfer of vapor pressure "humidity" WITHIN the snowpack and the additional load on the snowpack of humidity from the ATMOSPHERE (surface hoar, and negligible for "weight" reasons).

The first is important as it is the main process that will determine whether the layers are faceting or rounding. Without digging a full snow profile and taking the temperature gradient for the entire snowpack the easiest way to figure out what is probably happening is depth/air temp.

Deep (more than a meter) and warm (32+) promote rounding.

Shallow (less than a meter) and COLD promote faceting.

Neither adds weight to the snowpack, as I have already explained. It does shift where the mass in each crystal goes to. Rounding crystals actually don't loose or gain mass, but they shift mass from the sharper ridges to the valleys, making the grain more "round". As I said this creates a stronger layer, which may be a dangerous slab IF it is sitting on a weaker layer (like facets/surface hoar).

If ANYTHING the snowpack will lose some mass through sublimation during this whole process, though top layers will feel heavier as they compress, they have gained NO mass from atmospheric humidity.

"metamorphosis of snow by humidity is important in avalanches" - Yes... you are correct, all I am saying is it is not making the snowpack "heavier", perhaps more or less dense based on what I said above, but atmospheric humidity ONLY comes into play in the formation of Surface Hoar, which can be a very dangerous buried weak layer, but adds no noticeable "weight" to the snowpack... so I think we both agree, but the way it is explained can be tricky.

Reference: The Avalanche Handbook, 3rd Edition, considered the best technical book on the subject (and hundreds of hours taking courses through Level 3 AIARE, and spending time in workshops and seminars dedicated to snow science.)

And as for the Jackson lady, all I said was if she had a map & compass she could have walked herself to safety in 1 hour 45 minutes... better than spending the night out in those temps... but she kept her head and stayed alive. Not insulting her, simply stating what is COMMON knowledge. Map & Compass are the first two items on every gear list... how is that insulting?

I jump on an open slab, push it to try to trigger an avalanche...there is more danger that an avalanche from the roof of a house in quebec hit some one than an avalanche in mt Washington saturday: considerable danger of avalanche... with 9 inches of snow on the ground.

even if the condition was moderate few days ago, I doubt that an avalanche cause the accident in mt Washington. When I looked at central couloir, I don't see two or three feet of snow. Even with zero danger of avalanche, if someone don't kick hard enought to touch the ice...he will fall bringing snow with him. With the warm temperature and the big big big 9 inches of snow...I think that a water damn broke and bring the parties down the slab...In all consideration that I can make a mistake an a real avalanche happen. water damn is when the water run under a slab and stop the water. A pressure is form and when someone hike on it, it can broke and be dangerous for the climber. There is one or two in central couloir and in damnation I think

But I know that we can't trust what we read in journal

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DLottmann

I doubt that an avalanche cause the accident in mt Washington... if someone don't kick hard enought to touch the ice...he will fall bringing snow with him. With the warm temperature and the big big big 9 inches of snow...

12 witnesses who commented on the slide was waist deep, obvious avalanche debris, the fact it triggered right where the bulletin stated they were most concerned... yeah, ice dam... I see no motive for them to lie about that... it would have been less embarrassing had that been the case...

As for kicking hard enough to reach ice, Central Gully is 90% snow climb with one ice bulge. Haven’t you climbed it? You only need to “kick” for 20 feet... They were well above the only ice bulge on the climb, so I think your theory is lacking...

9 inches of snow is a lot, when combined with wind... but you know that already right? Snow will accumulate 3 to 5 times deeper in the lee areas like the top of Central Gully...